Format dates for synchronization

Use ISO format for data synchronization and user-friendly format for display.

src/components/AddTransactionButton.tsx

@@ -8,6 +8,7 @@ import { supabase } from '@/lib/supabase';
 import { isSyncEnabled } from '@/utils/syncUtils';
 import ExpenseForm, { ExpenseFormValues } from './expenses/ExpenseForm';
 import { Transaction } from '@/components/TransactionCard';
+import { normalizeDate } from '@/utils/sync/transaction/dateUtils';
 
 const AddTransactionButton = () => {
   const [showExpenseDialog, setShowExpenseDialog] = useState(false);
@@ -53,11 +54,14 @@ const AddTransactionButton = () => {
         const { data: { user } } = await supabase.auth.getUser();
         
         if (isSyncEnabled() && user) {
+          // ISO 형식으로 날짜 변환
+          const isoDate = normalizeDate(formattedDate);
+          
           const { error } = await supabase.from('transactions').insert({
             user_id: user.id,
             title: data.title,
             amount: parseInt(numericAmount),
-            date: formattedDate,
+            date: isoDate, // ISO 형식 사용
             category: data.category,
             type: 'expense',
             transaction_id: newExpense.id